1. Field of the Invention
The present invention relates to a method of casting an engine block of aluminum whose working surfaces, after milling the interiors of the cylinders, are coated with a harder metal, particularly nickel.
2. Description of the Related Art
Engine blocks of aluminum require a harder metal at the working surfaces.
One possibility of providing the harder metal by the casting alloy itself is to use a hypereutectoid alloy which precipitates silicon. The cast article then has sufficient hardness and resistance to wear for forming the working surfaces directly. The manufacture can be carried out by the sand casting method.
Engine blocks of a hypoeutectoid alloy are provided with cylinder inserts with gray cast iron which are cast in or they are provided with a galvanically applied coating of nickel. The coating with nickel requires a surface quality which in the past could only be produced by the permanent mold casting method. However, permanent mold casting is frequently work intensive, primarily because of the removal from the mold and the variety of possible shapes is smaller than compared to the sand casting method. The engine blocks with the inserts of gray cast iron are also manufactured by the permanent mold casting method.